Driving method for switching circuit power converter and driving module thereof
The present invention is a switching circuit driving method for power converters and its driving module. Such driving method and driving module can avoid the occurrence of valley jumping by replacing the original blanking time with a front blanking time or a back blanking time when a valley jumping occurs in the system, and avoid the noise problem caused by valley jumping.
1. A driving method for a switching circuit of a power converter, which is performed by a driving module, wherein windings of said switching circuit include a parasitic oscillation with multiple valleys, said driving method comprising steps of:
said driving module calculating an original blanking time according to an output power of said power converter;
said driving module calculating to generate a front blanking time and a back blanking time according to said original blanking time, said front blanking time being shorter than said original blanking time, and said back blanking time being longer than said original blanking time;
said driving module performing valley switching detecting, identifying an ordinal number of one of said valleys at which the switching circuit is switched, wherein said original blanking time is replaced by said back blanking time if said ordinal number is increased, and said original blanking time is replaced by said front blanking time if said ordinal number is decreased; and
detecting a first valley right after said original blanking time, said back blanking time, or said front blanking time, and controlling said switching circuit to switch.
2. The driving method for the switching circuit of the power converter of claim 1 , where after said step of replacing said original blanking time by said back blanking time or said front blanking time, maintain using said back blanking time or said front blanking time for achieving at least a debounce time.
3. The driving method for the switching circuit of the power converter of claim 1 , wherein said front blanking time is generated by subtracting a first deadzone time from said original blanking time; and said back blanking time is generated by adding a second deadzone time to said original blanking time.
4. The driving method for the switching circuit of the power converter of claim 3 , wherein said first deadzone time is identical to said second deadzone time.
5. The driving method for the switching circuit of the power converter of claim 3 , wherein; said parasitic oscillation includes a resonant period; and said first deadzone time and said second deadzone time are greater than or equal to said resonant period.
6. The driving method for the switching circuit of the power converter of claim 5 , further comprising a step of calculating said resonant period according to said parasitic oscillation.
7. A driving module, coupled to a switching circuit of a power converter, wherein windings of said switching circuit include a parasitic oscillation with multiple valleys, said driving module comprising:
a blanking-time calculation unit, calculating an original blanking time according to an output power of said power converter, and generating a front blanking time and a back blanking time according to said original blanking time; and
a valley switching detection unit, coupled with said blanking-time calculation unit, said valley switching detection unit identifying an ordinal number of one of said valleys at which the switching circuit is switched, replacing said original blanking time by said back blanking time if said ordinal number is increased, and replacing said original blanking time by said front blanking time if said ordinal number is decreased.
8. The driving module of claim 7 , wherein said valley-switch detection unit is coupled to a control node of a multiplexer, and said blanking-time calculation unit is coupled to inputs of said multiplexer; said multiplexer outputs one of said blinking time, said back blanking time, and said front blanking time according to control of said valley-switch detection unit.
9. The driving module of claim 7 , and further comprising a debounce unit, coupled to said valley-switch detection unit, wherein said blanking-time calculation unit is coupled to inputs of a multiplexer, and said debounce unit is coupled to an control node of said multiplexer, for controlling said multiplexer to output one of said blinking time, said back blanking time, and said front blanking time according to control of said valley-switch detection unit, and maintaining a debounce time.
10. The driving module of claim 8 or claim 9 , and further comprising a valley-signal generation unit, said valley-signal generation unit generating a pulse signal of each valley according to the parasitic oscillation of said windings, said valley-signal generation unit detecting a first valley after said original blanking time, said back blanking time, or said front blanking time according to said pulse signal and the output of said multiplexer, and controlling said switching circuit to switch.
11. The driving module of claim 7 , wherein said front blanking time is generated by subtracting a first deadzone time from said original blanking time; and said back blanking time is generated by adding a second deadzone time to said original blanking time.
12. The driving module of claim 11 , wherein said first deadzone time is greater than said second deadzone time.
13. The driving module of claim 11 , wherein said parasitic oscillation includes a resonant period; and said first deadzone time and said second deadzone time are greater than or equal to said resonant period.
14. The driving module of claim 13 , wherein said blanking-time calculation unit calculates said resonant period according to said parasitic oscillation.
15. The driving module of claim 11 , wherein said blanking-time calculation unit includes an output-power calculation circuit for calculating the output power of said power converter.